Java Message Format Using Named Placeholder

The Java MessageFormat class allows user to pre-define a string with placeholders and then fill the placeholders with actual strings later to construct a proper message.

It's all fine if you're used to numbered placeholders e.g. {0} and {1}.

Apache Commons has a StrSubstitutor class which allows use of named placeholders.

Although StrSubstitutor is a bit more verbose, but it helps when you're handling lots of key/value pairs.

import java.util.HashMap;

import java.util.Map;

import org.apache.commons.lang3.text.StrSubstitutor;

public class MessagePlaceHolder {

     

      public static void main(String[] args) {

            Map<String,String> map = new HashMap<String, String>();

            map.put("name", "Rajesh");

            map.put("email", "rkdixit3@gmail.com");

           

            String format = "Hello {name}, your email is {email}.";

            String message = StrSubstitutor.replace(format,map,"{","}");

            System.out.println(message);

      }

}

Output:

Hello Rajesh, your email is rkdixit3@gmail.com.

How to format messages in Java?

MessageFormat

The MessageFormat class can be used quite nicely to compose messages.

MessageFormat takes a set of objects, formats them, then inserts the formatted strings into the pattern at the appropriate places.

import java.text.*;

public class MessageFormator {

     public static void main(String[] args) {

           String message="Request id# {0} will be resolve till {1}.";

           Object values[] = { "1325", "25-Mar-2016" };

           String s = MessageFormat.format(message, values);

           System.out.println(s);

    }

}

Output:

Request id# 1325 will be resolve till 25-Mar-2016.